Spark plug testing kit

Abstract

There is provided a spark plug testing kit for safe and convenient testing of petrol engines. The testing kit has a spark observation device within which a spark gap of a spark plug installed therein may be observed in use. The kit has a positive lead for connection to the engine distributor and an earth lead configured for connection to a spark plug opening engaging device. The spark plug engaging opening device comprises threading for turning into a spark plug socket of an engine block and defines an elongate male electrical connection nut standing proud therefrom over which a corresponding electrical connection of the earth lead may be easily and safely electrically connected. The spark plug engaging opening device further comprises exhaust ports through a side of the device for engine decompression during cranking.

The invention claimed is: 
     
       1. A spark plug testing kit comprising:
 a spark observation device having a transparent observation chamber for viewing a spark gap of a spark plug installed therein in use; 
 positive and earth leads for electrically connecting the spark observation device at respective proximal ends thereof; and 
 a spark plug opening engaging device, wherein:
 the spark plug opening engaging device is
 elongate; 
 defines threading at a first end thereof for turning into a spark 
 
 plug opening of an engine block; and
 defines an elongate electrical connector nut at a second end thereof, opposite the first end, where a side member spans between the first end and the second end; 
 
 a distal end of the earth lead comprises an electrical connector configured for engagement over the elongate electrical connector nut and having an insulative sheath thereabout; and 
 the spark plug opening engaging device defines at least one engine depressurisation exhaust port through the side member of the spark plug opening engaging device, the depressurisation exhaust port permitting flow of fluid from inside the spark plug opening engaging device to outside the spark plug opening engaging device. 
 
 
     
     
       2. A spark plug testing kit as claimed in  claim 1 , wherein the proximal end of the earth lead comprises a collar for electrical contact with the head of the spark plug. 
     
     
       3. A spark plug testing kit as claimed in  claim 1 , wherein the transparent observation chamber is substantially dome shaped so as to allow for the viewing of the spark gap from differing angles. 
     
     
       4. A spark plug testing kit as claimed in  claim 3 , wherein the transparent observation chamber comprises transparent polycarbonate. 
     
     
       5. A spark plug testing kit as claimed in  claim 1 , wherein the spark observation device comprises a cylindrical portion and a terminal head portion and wherein the cylindrical portion and a terminal head portion are configured to fasten together to secure the spark plug therebetween in use. 
     
     
       6. A spark plug testing kit as claimed in  claim 5 , wherein the terminal head portion comprises an annular extrusion comprising an outward thread for turning into a complimentary inner thread of the transparent observation chamber to house the spark gap in a transparent manner. 
     
     
       7. A spark plug testing kit as claimed in  claim 1 , wherein a distal end of the positive lead comprises a positive lead terminal. 
     
     
       8. A spark plug testing kit as claimed in  claim 7 , wherein the positive lead terminal is substantially elongate for insertion into a distributor lead connector. 
     
     
       9. A spark plug testing kit as claimed in  claim 8 , wherein the positive lead terminal comprises a proximal insulation sheath. 
     
     
       10. A spark plug testing kit as claimed in  claim 1 , wherein the spark plug opening engaging device comprises a hex nut profile cross section between the threading and the elongate electrical connector nut. 
     
     
       11. A spark plug testing kit as claimed in  claim 1 , wherein the elongate electrical connector nut defines an end section and a waist in from the end section and wherein the waist has a diameter less than a maximum diameter of the end section. 
     
     
       12. The spark plug testing kit as claimed in  claim 1 , wherein each of the at least one engine depressurisation exhaust port expels fluid from the inside space in a single direction. 
     
     
       13. The spark plug testing kit as claimed in  claim 6 , further comprising a cut-out formed in the terminal head portion for passage of a collar of the earth lead.